KR20010074528A - Method for protecting wood and wooden articles from fungal infection - Google Patents

Abstract

PURPOSE: A method for protecting wood by treatment with sorbic acid and/or one or more salts of sorbic acid is provided. CONSTITUTION: Immersion Impregnation with Aqueous Potassium Sorbate Solution Air-dry pine boards are dipped into a solution of 30% potassium sorbate in water for event, visible soaking of the surface. After the treatment they are air dried. The boards are then stored in the open and only protected against direct rainfall at usual room temperature together with untreated boards for three weeks. After completion of the storage the untreated boards have intensive blue stain infection, which covers virtually the entire surface, while the treated boards, despite storage directly next to the infected boards, remain free from fungal infection. Compared with fresh wood, there is only a staining to give a pale brown color.

Description

How to protect wood and wooden products from fungal infections {Method for protecting wood and wooden articles from fungal infection}

In a humid environment, wood is susceptible to fungi and other fungi. Many fungi can cause damage to wood. This includes a variety of wood-contaminated fungi that can grow relatively rapidly on unpreserved wood surfaces and weather exposed wood surfaces. In untreated wood, there is often a contamination that can be caused, for example, by Aureobasidium pullulan. It is known by the name "blue stain". The growth of these fungi not only impairs the appearance of the wood or products made from it, but also risks the fungus is transferred from the wood to other products or products and even long-lasting mold is released into the ambient air. If sensitive people inhale these fungi, they may get asthma, for example.

In order to protect wood and wood products from fungal infections, a number of components and treatments have been proposed.

For example, wood can be protected by drying to lower the H ₂ O content. Fungi can grow in the presence of water, generally at least about 20% water. However, when the dried wood is exposed to the weather at relatively high relative humidity, the drying effect is soon lost.

Paints, varnishes and similar cladding also prevent fungi from penetrating or penetrating into the wood surface. Although these methods have proved practical, some of them are labor-intensive or expensive and are only effective if the wood or wood products do not pass through a humid environment or the pigments or cladding are not damaged. However, during transport and other mechanical stresses, they are susceptible to damage and at least part of their protective action is lost.

In addition, a number of components having fungicidal action, which are used as a preservative for wood, such as tar oil, organic tin compounds, various chlorinated aromatic and aliphatic compounds, and other compounds which may be used alone or in combination, are known. It is. Most of these components are characterized by excellent activity against fungi. Their use is generally simple. In most cases, impregnation can permanently protect wood from fungal infections. However, these ingredients have the disadvantage of being characterized by some toxicity that can be problematic when used in sensitive areas. This problem arises especially when used in the food manufacturing field, even if only a small amount can be reliably excluded from being transferred to food or food packaging. In particular, in the case of strong wood preservatives such as tar oil for wood, even if the trace amount in the food, there is a risk of bad smell. Indeed, nevertheless, consistently that wood cargo pallets, especially those that transport and deliver raw materials, can be infected by wood-degrading fungi during transport and storage and move along with the cargo pallets to storage and manufacturing areas causing hygiene problems. It is observed.

Several preservatives used to preserve various foods have been previously tested for their applicability for preserving wood, particularly in the form of derivatives which are not used in food preservation per se. For example, the water-insoluble zinc salt of sorbic acid is described as inert (see literature; Holzforschung 17, 97, 1963). Due to its more robust structure, it is not completely consistent with the coniferous wood commonly used in Germany and thus relates to the utility of commercially available sodium sorbate for bamboo, which can be somewhat more easily protected from fungal infections. Studies generally infected with fungi in a few days, resulting in worse results than dehydroacetic acid tested as a control. In these studies, sodium sorbate showed activity only at pH 3.0, which is not really common (see literature; Hakko Kogaku Zasshi 37, 19, 1959).

Since food preservatives and derivatives thereof have been considered to be inadequate in activity, they are not actually used as wood preservatives. However, unlike wood preservatives used in industrial applications, preservatives used in food processing are harmless to health, so that trace amounts are transferred to food packaging materials rather than industrial preservatives. In addition, since they are not strong in smell, they do not deteriorate the aroma of food. They are particularly related to sorbic acid, which is structurally closely related to fatty acids present in food fats and is broken down as fatty acids in the same way in body metabolism.

Surprisingly, it has now been found that sorbic acid, in particular its water-soluble salts, can completely protect wood and wood products from wood damaging fungi for a relatively long time in a humid environment. This protective action generally refers to the fact that sorbic acid and its salts are active only at the acidic pH of the substance to be protected. Handbuch Lebensmittelzusatzstoffe (Food additives manual), section B II-1.2, p. 3, 1997, but is also achieved when the pH of the wood is higher.

Accordingly, the present invention relates to wood impregnated with sorbic acid and / or one or more salts of sorbic acid.

The present invention also relates to a method for protecting wood comprising treating wood with sorbic acid and / or one or more salts of sorbic acid.

In the present invention, the salts of sorbic acid are especially water-soluble salts, preferably sodium salts, potassium salts and magnesium salts.

The protective action of sorbic acid and its salts is interesting and important, in particular for cargo pallets for raw materials for food production. Such cargo pallets are exposed to a wide variety of conditions during transportation and storage, including several environments, such as exposing the cargo pallets under high humidity when the material loaded on the cargo pallets is protected from moisture by overpacking. do. Thus, protecting cargo pallets from fungal infections is not straightforward. However, after treating wood with salts of sorbic acid, it has been found that even in wet conditions, fungi remain uninfected for a relatively long time, even under corresponding conditions that actually exceed the standard circulation of cargo pallets. . In this way, unwanted wooden lumber pallets used in wood and wood products, especially in food manufacturing and food processing, without the risk of transporting trace amounts of conventional wood preservatives that are harmful to health and have an unpleasant odor to food or food packaging. It can protect against fungal infections.

Wood can be protected from fungi simply by treatment with a salt solution of sorbic acid without the need for special or complex application or impregnation methods that go beyond the conventional methods used for wood processing. Any method is suitable as long as the surface of the wood or wood product can be uniformly wetted with a solution of sorbic acid and / or sorbate salts, ie dipping, spraying, coating and other methods. The concentration of sorbic acid and / or salts of sorbic acid should be consistent with the intended treatment. They can in principle vary within wide limits, the upper limit being limited by the solubility limit and the lower limit being limited by low protective action at insufficient concentrations. Limited protective action can be achieved even at some weight percent, especially when using dry wood and the absorption of the solution is facilitated by a relatively long immersion time or the wood is intensively wetted by spraying or coating. Typically, salt solutions in water or alcohols (eg branched or straight chain C ₁ -C ₄ alkanols and / or C ₂ -C ₄ alkanediols) or mixtures of these alcohols and water, in particular aqueous 1,2-propanediol It is preferably used at a concentration of 1 to 50% by weight, in particular 3 to 30% by weight, particularly preferably 10 to 40% by weight. Solutions of sorbate salts in water are preferred, but under special conditions, solutions in a mixture of water and volatile alcohols can be used for rapid drying, and less volatile alcohols can be used to avoid crack formation when dried too rapidly. have.

For particularly strong protective action, pressure impregnation or impregnation after a prior discharge can be carried out instead of simple soaking treatment, in each case sorbic acid and / or sorbic acid in water or a mixture of water and 1,2-propanediol Salt solution is used.

After treatment, it is generally sufficient to simply dry in dry air to achieve the desired protective action. Alternatively, it is also possible to accelerate dry in a heated room or chamber or in a warm or dry air stream.

The treatment is preferably carried out in the wood section to be further processed such that the entire surface is in uniform contact with sorbic acid and / or salts of sorbic acid. However, if the entire surface in the form of finished wood products can be contacted with a solution of sorbic acid and / or sorbate salts, it may be treated on the finished wood product.

Surprisingly, wood or wood products can be protected without the adverse effects allowed. In particular, wood and wood products can actually be odorless. Although it may discolor to brown after treatment, this is a very desirable phenomenon and will be considered somewhat more satisfactory than, for example, untreated white wood or pine wood. The treatment does not impair the elasticity of the wood and its strength.

The invention is illustrated by the following examples.

Example 1

Immersion Impregnation with Potassium Sorbate Aqueous Solution

Air-dried pine planks are immersed visually soaked in 30% potassium sorbate solution in laboratory water. After treatment, it is air dried. The planks are then stored for 3 weeks in an open place, blocking only direct rainfall at normal room temperature with the untreated planks. After completion of storage, the untreated planks exhibited intensive stool infection, with the stool infection covering almost the entire surface, whereas the treated planks did not show a fungal infection despite being stored next to the infected plank. Compared to the wood that has not been preserved, there was a stain that only showed light brown.

Example 2

Immersion impregnation using potassium sorbate solution in aqueous 1,2-propanediol

Air dried pine planks were immersed in a 30% potassium sorbate solution in a mixture of 75% by volume water and 25% by weight of 1,2-propanediol as in Example 1, and further treated and stored. After completion of storage, the board also showed no fungal infections. In comparison with Example 1, the brown stains of the planks became somewhat stronger.

Example 3

Spray Treatment with Potassium Sorbate Aqueous Solution

Air dried pine planks are sprayed with spray pistol using a 20% potassium sorbate solution in water until the surface is evenly wetted. The planks are then dried and stored as in Example 1. After completion of storage, the results were consistent with Example 1.

Example 4

Storage at high atmospheric humidity

In each case, two pine planks are immersed in potassium sorbate solution (concentrations see Table 1) and stored at 35 ° C. in saturated steam atmosphere. In parallel with this, in order to further contaminate the surface with mold, two pine planks each are further contaminated with soil on the surface after immersion. In order to rule out cross-contamination, each board is packed separately in a film and thoroughly examined for fungal infection. The results are shown in Table 1.

Preservation time (minutes) in potassium sorbate solution Concentration of Potassium Sorbate Solution (wt%) Pollution by soil Fungal infections K1 - - - Appears from day 29 Significant from day 53 V1 10 One none None after 81 days V2 10 2 none None after 81 days V3 10 5 none None after 81 days V4 5 10 none None after 81 days K2 - - has exist Appears on day 29, increases with storage V5 10 One has exist Appears slightly after 43 days V6 10 2 has exist Slightly present from day 53 V7 10 5 has exist None after 81 days V8 5 10 has exist None after 81 days

The method according to the invention protects wood from fungi by simply treating with a solution of sorbic acid and / or sorbate salts, without the need for special or complex application or impregnation methods that go beyond the conventional methods used for wood treatment. can do.

Claims (15)

Wood impregnated with sorbic acid and / or one or more salts of sorbic acid. The wood according to claim 1, wherein the salt of sorbic acid is the sodium salt, potassium salt and / or magnesium salt of sorbic acid. The wood of claim 2, wherein the salt is potassium sorbate. The wood according to claim 1, wherein sorbic acid and / or salts of sorbic acid are dissolved in water, alcohols, or mixtures of alcohols with water. The wood according to any one of claims 1 to 4, wherein the salt (s) of sorbic acid and / or sorbic acid are used in the treatment liquor at a concentration of 1 to 50% by weight, preferably 3 to 30% by weight. . A method of preserving wood by treating with sorbic acid and / or one or more salts of sorbic acid. The process of claim 6 wherein the treatment of sorbic acid and / or sorbic acid with one or more salts is carried out in water, an alcohol, or a mixture of water and one or more alcohols. 8. The method of claim 7, wherein the alcohol is 1,2-propanediol. 8. Process according to claim 6 or 7, wherein sorbic acid and / or salt (s) of sorbic acid are used in the treatment liquid at a concentration of 1 to 50% by weight, preferably 3 to 30% by weight. The method according to any one of claims 6 to 9, wherein the treatment is carried out in the form of immersion impregnation. The method according to any one of claims 6 to 10, wherein the treatment is performed at elevated pressure. The method according to claim 6, wherein the wood is exposed to reduced pressure prior to treatment. The method of claim 7, wherein the solution of sorbic acid and / or sorbic acid salt is applied to the surface by spraying or coating. Use of sorbic acid and / or salts thereof for preserving wood. 15. Use according to claim 14 for protecting wood from fungal infections.